From the iceberg-strewn waters above the Arctic Circle to the turquoise tropics of the Caribbean, Captain Karen Miles makes her home on the sea. She has a sweet, warm demeanor and a kind face, but they belie a cast-iron determination. This Rockland-born Mainer pushed past the boundaries of expectation and found her calling.

Karen’s grandfather, a fishing industry manager, was never a seagoing man, but he was tough and demanding. When Karen had birthdays as a girl, her grandfather used to hand her a chunk of rock — limestone, feldspar, petrified wood.

“Here,” he would say to her; “Go look it up and learn about it.”

“I didn’t really appreciate it then,” said Karen, “but I do now.”

Attention to detail and the drive to learn came from her grandfather, but love of the sea came from Karen’s dad. His passions led him to become a lobster fisherman and scallop diver. Karen and her brother grew up constantly in and around boats.

In the 1970s, however, fishing was a milieu that did not welcome women. Karen loved marine science and biology; she was certified in scuba diving and did propeller work on Coast Guard vessels; but she never fished with her father, which frustrated her. “I didn’t go on the boat because I was a girl,” she said.

Karen went to school in Boston to study interior design, and worked for an architectural firm during the day to pay for her classes. First she did office jobs, but before long, Karen found herself doing drafting work, and eventually woodworking and building models.

“I realized that design was not intense enough for my personality,” she said. “I was feeling hollow.”

Karen loved the solid satisfaction of a finished product under her hands, and enrolled in a furniture craft course. Her design and woodworking talents were to become essential aspects of her future life at sea.

That life began when Karen was invited to spend a few months on a square-rigged ship. “I’ve been pretty much on ships ever since.” Before her first trip, she bought and read a copy of “Chapman Piloting and Seamanship,” which was “such a nerdy thing to do.” But it is in Karen’s nature to learn everything she can about whatever task she undertakes.

Karen met her husband, Capt. Rick Miles, somewhere out on Penobscot Bay. Their shared love of the sea, and of fostering appreciation for maritime people, animals, and history, first brought them together. Then they built their lives around introducing other people to their world.

Karen lights up when she tells of their search for the steel-hulled vessel that would become their livelihood. The ship they named The Wanderbird was an old North Sea fishing trawler coated in a veneer of fish smells and Formica. You should see it now:

The Wanderbird sleeps 12 guests, up to eight crew, the two captains, a few dogs and a macaw. Karen oversaw the design transformation of the ship’s interior — now graced with warm mahogany, arched windows, rattan chairs — it is awash in old-style atmosphere and comfort.

Together, Karen and Rick host expeditions around the Maine coast, along the northern coasts to Greenland, and more recently to the waters around Culebra in the Caribbean. They have forged a fulfilling life.

With her gentle perseverance, Karen pushed against conventional stereotypes, both in her career and at home. When she was 27, her father was injured, but setting out nonetheless for a day of lobstering on choppy seas. For the first time, her mother told Karen, “OK, go with him today.”

When they returned to the pier, an old fisherman asked her dad, “Did she get sick?”

“She had a great time!” her father answered proudly.

Now Karen goes fishing with her father at the end of every season.

“A lot of people do what they think they’re supposed to do, or expected to do,” Karen said. “Hopefully, sooner or later they figure out what really strikes a chord inside them.”